Device and method for protection from radiation in space

ABSTRACT

A device for protection of a body from radiation includes at least one flexible garment. Each section of the flexible garment is configured to shield a region of a surface of the body. Each section complementarily attenuates self-shielding by internal structure between the region and an interior region of the body such that radiation at the interior region is attenuated to a predefined attenuation level.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application of PCT InternationalApplication No. PCT/IL2016/050298, International Filing Date Mar. 17,2016, claiming the benefit of US Provisional Patent Applications Nos.62/134,274, filed Mar. 17, 2015, and 62/239,886, filed Oct. 10, 2015,all of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to protection against ionizing radiation.More particularly the present invention relates to a radiationprotection device and method for use in space.

BACKGROUND OF THE INVENTION

On space missions beyond low Earth orbit, such as on missions to Earth'smoon, to Mars, or elsewhere, Earth's atmosphere and magnetosphere arenot available to protect the crew of the mission from sources ofionizing radiation. Such radiation may include the solar wind, cosmicradiation, solar flares or other solar particle events, and otherradiation sources or events. Effects of exposure to radiation from amajor solar event or other radiation event could place the crew of aspace mission at significant risk for acute radiation sickness. Suchacute exposure could impact crew health and performance during theirmission, endangering completion of the mission and the safe return ofthe crew to Earth. Protracted exposure to lower levels of radiation(e.g., the solar wind or cosmic radiation) may increase the likelihoodof cancer or other radiation-induced disorders for crew members manyyears after the completion of their mission.

Shielding the entire habitable area or cabin of a spacecraft is notcurrently feasible. Effectively shielding an entire crew module (such asthat of the Orion spacecraft) would require very large quantities ofshielding material. Delivering such a quantity of shielding material tospace would entail much added expense and time, or would require use ofa lunch vehicle that is larger than any that are expected to beavailable in the foreseeable future. Addition of the extra mass withouta corresponding increase in propulsion power could increase travel timeto a destination, increasing exposure to the radiation. In addition,such cabin shielding would not provide any shielding for an astronautsduring and extravehicular activities.

Drugs are under development to mimic or enhance the body's naturalcapacity to repair damage caused by radiation. Although there has beensome progress in development of drugs for countering the effects ofterrestrial ionizing radiation, such as gamma radiation, very littleprogress has been made towards countering the effects of the type ofradiation (high-energy and massive charged particles) that isencountered during space travel. If such a drug were to be developed, itwould probably have to be administered several hours before exposure.However, solar particle events cannot currently be forecast in advance.Furthermore, pharmaceuticals have been found to become unstable duringspace travel, possibly due to protracted exposure to radiation andvibration.

Magnetic deflection and electrostatic repulsion has been considered forreducing exposure to radiation in space. However, a compact system mayrequire magnetic field strength as large as 10 tesla to 20 tesla. Suchhigh fields have been known to produce headaches and migraines inmagnetic resonance imaging patients, and long-duration exposure to suchfields has not been studied. Devices to produce such a magnetic fieldmay add thousands of kilograms to the mass of the spacecraft.

Personal shielding that is worn on an astronaut's or other user's bodyenables placement of the shielding adjacent to the area of coverage. Thesolid angle of coverage is thus maximized, thus enabling a reduction(relative to shielding of an entire cabin or spacecraft) in the mass ofshielding that is required to provide equivalent protection.

SUMMARY OF THE INVENTION

There is thus provided, in accordance with an embodiment of the presentinvention, a device for protection of a body from radiation, the deviceincluding at least one flexible garment, each section of the at leastone flexible garment being configured to shield a region of a surface ofthe body such that the each section complementarily attenuatesself-shielding by internal structure between the region and an interiorregion of the body such that radiation at the interior region isattenuated to a predefined attenuation level.

Furthermore, in accordance with an embodiment of the present invention,a garment of the at least one flexible garment includes a plurality ofshield elements incorporated into the flexible substrate.

Furthermore, in accordance with an embodiment of the present invention,the flexible substrate or the plurality of shield elements includes apolymer.

Furthermore, in accordance with an embodiment of the present invention,the plurality of shield elements is embedded within the flexiblesubstrate.

Furthermore, in accordance with an embodiment of the present invention,each of the plurality of shield elements has an inward facing surfacethat is greater than an opposite outward facing surface, such thattapering gaps are formed in between adjacent shield elements of theplurality of shield elements.

Furthermore, in accordance with an embodiment of the present invention,the substrate fully or partially fills the gaps.

Furthermore, in accordance with an embodiment of the present invention,the flexible substrate includes a foam.

Furthermore, in accordance with an embodiment of the present invention,the plurality of shield elements includes a plurality of sequins thatare attached to the flexible substrate and wherein the flexible surfaceincludes a fabric sheet.

Furthermore, in accordance with an embodiment of the present invention,the fabric sheet forms a webbing between the plurality of sequins.

Furthermore, in accordance with an embodiment of the present invention,a garment of the at least one garment includes a plurality of the fabricsheets formed into layers.

Furthermore, in accordance with an embodiment of the present invention,a sequin of the plurality of sequins on one fabric sheet of theplurality of the fabric sheets is positioned to overlie a gap betweenadjacent sequins of the plurality of sequins on another fabric sheet ofthe plurality of fabric sheets.

Furthermore, in accordance with an embodiment of the present invention,the plurality of shield elements includes a plurality of bags, each ofthe bags being configured to be filled with a liquid.

Furthermore, in accordance with an embodiment of the present invention,the flexible substrate includes a plurality of flexible bag holders,each of the plurality of bags being configured to be inserted into a bagholder of the plurality of flexible bag holders.

Furthermore, in accordance with an embodiment of the present invention,a shield element of the plurality of shield elements includes aplurality of stacked liquid-fillable compartments.

Furthermore, in accordance with an embodiment of the present invention,the device includes a tube to enable introduction of a liquid into aliquid-fillable compartment of the plurality of stacked liquid-Tillablecompartments or removal of the liquid from a liquid-fillable compartmentof the plurality of stacked liquid-fillable compartments

Furthermore, in accordance with an embodiment of the present invention,the at least one garment includes a plurality of garments that areconfigured to be worn in layers, wherein one garment of the plurality ofgarments is configured such that a shield element of the plurality ofshield elements on the one garment is configured to overlie a gapbetween two adjacent shield elements on another garment of the pluralityof garments.

Furthermore, in accordance with an embodiment of the present invention,the interior region includes tissue-resident stem cells.

Furthermore, in accordance with an embodiment of the present invention,the tissue-resident stem cells are selected from a group oftissue-resident stem cells consisting of distal airway stem cells of thelung, CD34+ hematopoietic stem cells, and intestinal LGR5+ stem cells.

There is further provided, in accordance with an embodiment of thepresent invention, a method for preventing a radiation-induced conditionin a body in space, the method including: determining a requiredattenuation of radiation at an interior region of the body so as toprevent the radiation-induced condition under an anticipated exposure ofthe body to radiation; determining self-shielding from the radiationcorresponding to each surface region of a plurality of regions of asurface of the body by determining attenuation of the radiation byinternal structure of the body that lies between the interior region andthe each surface region; and providing a radiation protection deviceincluding at least one flexible garment, each section of the at leastone flexible garment being configured to attenuate radiation to ashielded surface region of plurality of regions of a surface of the bodyto complementarily attenuate the self-shielding by the shielded surfaceregion.

Furthermore, in accordance with an embodiment of the present invention,the radiation-induced condition includes mutagenesis or destruction ofstem cells and the interior region includes a stem cell niche.

Furthermore, in accordance with an embodiment of the present invention,determining the required radiation attenuation includes determining anattenuation required to prevent a Bragg peak of the radiation fromoccurring within the interior region.

Furthermore, in accordance with an embodiment of the present invention,determining the required attenuation of radiation includes determiningtotal areal density of shielding to the interior region to prevent theradiation-induced condition, the determined self-shielding includes anareal density of the internal structure that lies between the interiorregion and the each surface region, and wherein an areal density of theeach section is at least a difference between the total areal densityand the areal density of the internal structure.

BRIEF DESCRIPTION OF THE DRAWINGS

In order for the present invention, to be better understood and for itspractical applications to be appreciated, the following Figures areprovided and referenced hereafter. It should be noted that the Figuresare given as examples only and in no way limit the scope of theinvention. Like components are denoted by like reference numerals.

FIG. 1 schematically illustrates a radiation protection device, inaccordance with an embodiment of the present invention.

FIG. 2 schematically illustrates garment layers of the radiationprotection device shown in FIG. 1.

FIG. 3A schematically illustrates a garment layer of a radiationprotection device with shield elements that are embedded in a flexiblesubstrate, in accordance with an embodiment of the present invention.

FIG. 3B schematically illustrates bending of the garment layer shown inFIG. 3A.

FIG. 4A schematically illustrates an inner garment layer with embeddedshield elements of a radiation protection device, in accordance with anembodiment of the present invention.

FIG. 4B schematically illustrates a middle garment layer with embeddedshield elements worn over the inner garment layer shown in FIG. 4A.

FIG. 4C schematically illustrates an outer garment layer with embeddedshield elements worn over the garment layers shown in FIG. 4B.

FIG. 5A schematically illustrates an inner garment layer of a radiationprotection device, the garment layer having shield elements in the formof sequins, in accordance with an embodiment of the present invention.

FIG. 5B schematically illustrates a middle garment layer with shieldelements in the form of sequins and worn over the inner garment layershown in FIG. 5A.

FIG. 5C schematically illustrates an outer garment layer with liquidshield elements worn over the garment layers shown in FIG. 5B.

FIG. 5D schematically illustrates a cross section of a liquid layersection of the outer garment layer with liquid shield elements shown inFIG. 5C.

FIG. 6A schematically illustrates a sheet of the sequin shield elementgarment layer shown in FIG. 5A.

FIG. 6B schematically illustrates multiply layered sheets of the sequinshield element garment layer shown in FIG. 5A.

FIG. 6C schematically illustrates bending of the sequin shield elementgarment layer shown in FIG. 6B.

FIG. 7 schematically illustrates bending of the garment layer withliquid shield elements of a radiation protection device shown in FIG.5C.

FIG. 8 is a flowchart depicting a method for preventing aradiation-related condition in a living body, in accordance with anembodiment of the present invention.

FIG. 9A schematically illustrates a front part of a map of selfshielding by body tissue for radiation-sensitive internal regions in aperson, for use in design of a radiation protection device in accordancewith an embodiment of the present invention.

FIG. 9B schematically illustrates a rear part of the self-shielding mapshown in FIG. 9A.

FIG. 10A schematically illustrates a map of a distribution of radiationshielding on a front of a radiation protection device that is designedin consideration of the self-shielding map shown in FIG. 9A.

FIG. 10B schematically illustrates a map of a distribution of radiationshielding on a rear of a radiation protection device that is designed inconsideration of the self-shielding map shown in FIG. 9B.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those of ordinary skill in the artthat the invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components, modules,units and/or circuits have not been described in detail so as not toobscure the invention.

Although embodiments of the invention are not limited in this regard,discussions utilizing terms such as, for example, “processing,”“computing,” “calculating,” “determining,” “establishing”, “analyzing”,“checking”, or the like, may refer to operation(s) and/or process(es) ofa computer, a computing platform, a computing system, or otherelectronic computing device, that manipulates and/or transforms datarepresented as physical (e.g., electronic) quantities within thecomputer's registers and/or memories into other data similarlyrepresented as physical quantities within the computer's registersand/or memories or other information non-transitory storage medium(e.g., a memory) that may store instructions to perform operationsand/or processes. Although embodiments of the invention are not limitedin this regard, the terms “plurality” and “a plurality” as used hereinmay include, for example, “multiple” or “two or more”. The terms“plurality” or “a plurality” may be used throughout the specification todescribe two or more components, devices, elements, units, parameters,or the like. Unless explicitly stated, the method embodiments describedherein are not constrained to a particular order or sequence.

Additionally, some of the described method embodiments or elementsthereof can occur or be performed simultaneously, at the same point intime, or concurrently. Unless otherwise indicated, the conjunction “or”as used herein is to be understood as inclusive (any or all of thestated options).

In accordance with an embodiment of the present invention, a personalradiation protection device is configured to differentially shielddifferent regions of a body from one or more types of space radiation.The radiation protection device is in the form of one or more garmentsthat may be worn over the body. As used herein, a body refers to a bodyof a living human or animal (although for research, evaluation, ortesting purposes, the garment may used to shield a cadaver, phantom, orother inanimate object).

As used herein, space radiation refers to radiation that is primarily inthe form of energetic massive particles (e.g., baryonic particles, suchas protons, neutron, light or heavy nuclei, or other baryons, ormesons). Typical sources of space radiation may include solar flares orother solar particle events, galactic cosmic radiation, the solar wind,or other sources of energetic baryons or mesons. In some cases,interaction of the space radiation with matter may generate secondaryradiation that may include energetic photons (e.g., x-ray or gammaradiation) or other energetic particles (e.g., leptons, baryonic matter,or mesons).

As used herein, differential protection, shielding, or attenuationrefers to shielding (e.g., quantified by a local attenuation value or anareal mass density) by laterally displaced different sections of thegarment or device). Each of the different section of the garment isconfigured to cover, and thus to shield from radiation, a differentregion of a surface of the body.

The attenuation by a section of the device may be configured tocomplement self-shielding by the body of an interior region of the body.Self-shielding corresponding to surface region of the body refers toherein as attenuation by (or areal density of) internal structure thatlies between that surface region and the interior region.

For example, a total shielding in the form of a total attenuation valueor areal density value may be predetermined for one or more differentinterior regions of the body (e.g., based on a known or suspectedhealth-related effect of radiation on that interior region).Self-shielding from radiation by intervening interior structure of thebody (e.g., tissue or other internal structure) between the interiorregion and the surface region may be known, calculated, measured, ordeterminable by application of a combination of the above. The sectionof the device that shields that surface region is referred to ascomplementarily shielding the interior region when the combinedattenuation by that section of the device and the self-shieldingcorresponding to the surface region that is shielded by that sectionprovides at least the predetermined total required attenuation. Forexample, when the attenuation is quantified as an attenuation factor,the combined attenuation is determined by multiplying the self-shieldingattenuation and the attenuation by that section of the device. When theattenuation is quantified as an areal density, the combined attenuationis determined by adding areal density of the self-shielding and theareal density of the section of the device.

As used herein, a garment refers to an item that may be worn on a bodyin the manner of an article of clothing (e.g., such as a vest, tunic,girdle, belt, sleeve, helmet, hat, or other similar wearable article),whether or not such an item would be worn otherwise as an article ofclothing (e.g., when radiation shielding is not required). For example,the device may include a plurality of separately wearable and removablegarments that may be worn in layered fashion, with outer garment layersworn over one or more inner garment layers. In some cases, a singlegarment layer may include multiple connected layers of material. Thegarments are designed to be worn by a user, such as an astronaut inspace either within or outside of (e.g., in an extravehicular activityfrom) a spacecraft.

Each garment layer of the radiation protection device includes aplurality of radiation shield elements that are incorporated into aflexible substrate. A flexible substrate includes a material that may befashioned into a garment. The flexible material is sufficiently flexibleor elastic such that when fashioned into a garment and worn by a person,the garment is capable of bending together with a part of the personthat is bent during performance of one or more anticipated tasks.

A shield element may include a solid material or a liquid that isconfined to a compartment or container. Typically, the density ofmaterial in the shield element is sufficiently greater than the densityof the flexible substrate such that attenuation by the flexiblesubstrate is negligible (e.g., insignificant with regard to predictionof the likelihood of occurrence of a radiation-induced condition).

Each shield element is configured to attenuate one or more types ofionizing radiation that pass through that shield element. As usedherein, a shield element is referred to as being incorporated into thesubstrate when an independently manufactured shield element is attachedto or incorporated into a separately manufactured substrate, when asubstrate is manufactured with shield elements that are embedded,inlaid, or otherwise incorporated into the substrate, or when ashielding liquid is contained within a compartment. For example, theflexible substrate may include a fabric or a foamy material (e.g., afoamy plastic material) that may be fashioned into a garment. Theflexible substrate may include a flexible plastic that is provided withcompartments that are fillable with a liquid, or with a bag, sack,pouch, bottle, or other container that is filled with a liquid. Theflexible substrate may include structure to enable or facilitateattachment or incorporation of the shield elements to the flexiblesubstrate. Such structure may include indentations, pockets, sleeves,pouches, loops, hooks, a surface of a hook-and-loop fastener, anadhesive or tacky surface, a ferromagnetic surface, or other attachmentstructure.

The shield elements are designed to absorb or otherwise provideshielding from the type of radiation that is expected to be encounteredduring travel outside of the protection provided by Earth's atmosphereand magnetic field. Such radiation may include energetic protons, orother ions or other charged particles. In order to shield against suchradiation, the shield elements may include dense hydrocarbons (e.g.,plastics), water, or other materials that are rich in hydrogen and otherlight nuclei. The radiation may include high energy ions, neutrons,gamma rays, or other high-energy photons or charged particles. In orderto shield against such radiation, the shield elements may include anelectron-rich material, such as a dense metal with a high atomic number(e.g., lead).

The configuration of the shield elements of the radiation protectiondevice may be designed in consideration of the sensitivity to radiationof the part or organ of the body that each part of the radiationprotection device is configured to cover and shield. For example,interior regions (e.g., tissue types or organs) of the body that mayrequire a relatively large amount of shielding (so as to providerelatively large attenuation of radiation that is directed toward thoseregions) may include those interior regions that are rich inhematopoietic stem cells, other tissue-resident stem cells, or tissuesor organs that have been found to be especially sensitive to a one ormore types of incident radiation. Such regions may include, for example,ovaries, lungs, colon, breasts, stomach, iliac bone marrow, or othertissues that require increased protection (e.g., as per recommendationsof the International Commission on Radiological Protection). Suchinterior regions are herein referred to as radiation-sensitive regions.

Interior regions that require increased protection may include organs,or in some cases, stem cell niches in organs or elsewhere that tend tohave an increased concentration of tissue-resident stem cells. Forexample distal airways of the lung may be rich in distal airway stemcells and the ileum section of the small intestine may be rich in LGR5+stem cells. Protecting such interior regions may enable tissueregeneration following acute exposure to radiation, while protectingagainst cancer of that organ (since preventing a mutation in a stem cellmay be equivalent to preventing a mutation in thousands of daughtercells).

Stem cell niches may include one or more types of stem cells. Forexample, the stem cells may include one or more of hematopoietic stemcells, distal airway stem cells, mesenchymal stem cells, Sca-1 stemcells, CD34+ hematopoietic stem cells, spermatogonia, intestinal LGR5+stem cells, p63+ Krt5+ stem cells, ovarian primordial follicle stemcells, thyroid progenitor cells, CD133 progenitor cells, and endothelialprogenitor cells.

The configurations of shield elements in different parts of theradiation protection device may differ from one another in one or morecharacteristics. For example, the shape, size, composition, distribution(e.g., density), structure, or other characteristics of shield elementsin one part of the radiation protection device may differ from thosecharacteristics in another part of the radiation protection device.Similarly, the characteristics of the shield elements (and of theflexible substrate) may differ from layer to layer of the radiationprotection device.

For example, a distribution of number of layers of shielding (e.g., ofshield elements incorporated into a substrate) among different sectionsof the radiation protection device may be determined by the degree ofprotection (e.g., quantified by attenuation of incident radiation) thatis to be provided to a surface region of the body that is covered bythat section. A section of the radiation protection device that isconfigured to be worn over an interior region of the body requiringgreater protection from radiation may include more layers of shieldingthan a section of the radiation protection device that is configured tobe worn over an interior region of the body requiring less protection.The thicknesses of the shield elements within a single layer may also bevaried in order to provide variable selective shielding to differentinterior regions.

A radiation protection device, in accordance with an embodiment of thepresent invention, is sufficiently flexible to enable at least limitedmovement by a person who is wearing the device. The movement may enablesufficient range of motion so that the person may be able to performanticipated tasks while wearing the radiation protection device (e.g.,bend a torso or limb through a predetermined bending angle. For example,a section of the radiation protection device may be configured to becompressed on one side of the device while a corresponding opposite(e.g., on an opposite side of the limb or torso) section is configuredto be stretched. The shield elements may be arranged on the flexiblesubstrate such as to not impede bending of the flexible substrate. Inthis case, a gap between shield elements on one layer may be covered andshielded by shield elements on one or more other layers of the radiationprotection. Layers of the radiation protection device may be configuredto slide relative to one another so as to further enable bending of thetorso or limb.

A radiation protection device that provides selective protection fromionizing radiation may be advantageous over a device that providesnon-selective protection. A radiation suit or similar device could beconfigured to provide an approximately constant adequate radiationprotection (e.g., suitable for the most sensitive interior region of thebody) to all parts of the body. Such a device could be so massive as toseverely impair or restrict mobility or maneuverability of personwearing the device, as well as increasing the thrust required to launchor propel a vehicle holding one or more of such devices (typically atleast one device per passenger).

Active bone marrow is rich in blood-forming hematopoietic stem cells(HSC). HSC concentrations are present in marrow a several locations inthe human body, including the hip, sternum, ribs, vertebrae, and skull.For example, in adults, the active bone marrow of the iliac bones of thehip may require more radiation protection than other parts of the body.On the other hand, the bone marrow in the skull provides the foremostconcentration of active bone marrow in early life and may thereforerequire more protection. Therefore, the distribution of radiationattenuation in a radiation protection device may be configured inaccordance with the age of an intended user. The distribution ofradiation protection for different interior regions of the body may beconfigured by configuring the type, thickness, and the distribution ofradiation attenuating materials that are incorporated into the radiationprotection device.

In some cases, the distribution of radiation attenuation in theradiation protection device may be configured to protect a predeterminedfraction of active bone marrow in the body or in a particular interiorregion of the body. The protected quantity may be determined byconsideration of the quantity of bone marrow that is typicallytransplanted into a patient to replace damaged or destroyed bone marrow.For example, the protected quantity of bone marrow may be in the range25% to 150% of a typical quantity of transplanted bone marrow.

In some cases, the distribution of radiation attenuation in theradiation protection device may be configured to prevent mutations inorgans, or regions of organs, that are rich in stem cells.Tissue-resident stem cells may be shielded by the radiation protectiondevice. This may enable the regenerative capacity of the stem cells toenable the body to recover from deterministic effects of radiation. Inthis manner, cell damage that could otherwise lead to cancer or otherradiation-induced conditions may also be averted.

In some cases, the distribution of radiation attenuating material in theradiation protection device may be configured in consideration of theinherent radiation attenuation due to various tissues (e.g., skin, bone,muscle, or adipose tissue) through which radiation would have to pass inorder to reach bone marrow or other interior regions that requireradiation protection. For example, the amount and distribution ofradiation attenuating material needed may be determined using theformula

${{A_{D}\left( {x,y,z} \right)} = \frac{A_{R}}{A_{T}}},$where A_(D) is a required radiation attenuation to be provided by theradiation protection device at point x, y, z within the user's body,A_(R) is the total required radiation attenuation at the point, andA_(T) is the radiation attenuation provided by the surrounding oradjacent tissue.

The hematopoietic system is highly sensitive to ionizing radiation.Doses of 70 rad (0.7 Gy) and above may cause decreased hematocrit,neutropenia, and lymphopenia, leading to anemia and immune suppression.Major bone marrow cell loss may occur with doses of 150 rad (1.5 Gy) ormore.

A radiation protection device, in accordance with an embodiment of thepresent invention, may be designed to attenuate one or more types ofincident ionizing level to an acceptable level. The acceptable level maybe determined in accordance with one or more effects of radiation on aperson's body.

FIG. 1 schematically illustrates a radiation protection device, inaccordance with an embodiment of the present invention.

Radiation protection device 10 is configured to be worn as one or moregarments by a user 11. Radiation protection device 10 may include one ormore separate garments that may be worn as layers one over another. Insome cases, radiation protection device 10 may include a layered garmentthat incorporates multiple layers that may or may not be separable fromone another.

As shown, radiation protection device 10 includes one or more garmentsin the form of a tunic. Other forms of garments are possible. Forexample, radiation protection device 10 may include one or more coats,aprons, hats, helmets, scarves, gloves, pants, skirts, capes, ponchos,vests, jackets, shirts, or other types of garments.

Each garment of radiation protection device 10 may include one or morestructures to facilitate donning and removal, while preventing thegarment from accidently falling off of user 11. For example, a garmentof radiation protection device 10 may include a closeable full-length orpartial opening that may be opened to facilitate donning and removal.The opening may be provided with one or more closing or fasteningstructures that may be closed or fastened to retain the garment in placeon user 11. For example, the closing or fastening structure may includeone or more flaps, straps, buttons, snaps, laces, hook-and-loopfasteners, buckles, magnets, zippers, clasps, or other closing orfastening structure. In some cases, a garment of radiation protectiondevice 10 may be configured to be donned or removed without opening anyclosing or fastening structure (e.g., may be pulled on over the head andraised arms of user 11).

Radiation protection device 10 is configurable to provide varyingdegrees of radiation protection (e.g., as quantifiable by radiationattenuation) or types of radiation protection (e.g., quantifiable by aratio of attenuation of one type or energy of radiation to attenuationof another type or energy of radiation) to different parts of user 11.For example, one or more of a thickness of radiation protection device10, a distribution of shield elements, a density, size, shape, orcomposition of shield elements, a number of layers, or anothercharacteristic of radiation protection device 10 may vary from sectionto section of radiation protection device 10.

For example, a lower-protection section 10 a of radiation protectiondevice 10 may be thinner or otherwise provide lower attenuation than ahigher-protection section 10 b of radiation protection device 10.Characteristics of the radiation protection that is provided byradiation protection device 10 to each interior region of user 11 may beselected in accordance with a sensitivity of each interior region ofuser 11 to one or more types of radiation. For example, a more sensitiveinterior region of user 11 may have a relatively high concentration ofstem cells, or may be otherwise more susceptible to mutagenesis, thananother less sensitive interior region of user 11. Radiation protectiondevice 10 may be configured such that, when worn by user 11, ahigher-protection section 10 b covers the more sensitive interior regionand a lower-protection section 10 a covers the less sensitive interiorregion.

For example, in some cases, lower-protection section 10 a may have anareal density of about 7 g/cm². A higher-protection section 10 b mayhave an areal density of about 19 g/cm². Other ranges may be appropriatefor different individuals (e.g., with different body shape or differentsensitivity to radiation) or for different anticipated exposure toradiation. For example, in some cases a minimum areal density of alower-protection section 10 a may be in the range from 0.1 g/cm² to 20g/cm². A maximum areal density of higher-protection section 10 b may bein the range from 4 g/cm² to 46 g/cm².

For example, the energy spectrum of particles that are emitted duringlarge solar particle events has been measured to range from 20 MeV to300 MeV. A 20 MeV proton at the low end of the spectrum may have a rangeof about 4.2 mm in water. A 100 MeV proton may have a range in water ofabout 76 mm. A 200 MeV proton may have a range in water of about 260 mm.A 300 MeV proton at the high end of the spectrum may have a range inwater of about 510 mm. Thus, shielding that includes materials that arerich in hydrogen but denser than water may be useful as at least aninner garment layer of radiation protection device 10. Furthermore,limiting the protection to those interior regions of the user 11 thatare most sensitive to the effects of radiation may enable effectiveprotection without excessively increasing the mass or thickness ofradiation protection device 10.

The degree of sensitivity to radiation of different interior regions ofuser 11 may vary from individual to individual. For example, sensitivityof an interior region of user 11 to one or more types of radiation mayby affected by an age and sex of user 11, by a medical history of user11, or by a health-related condition. For example, sensitivity of aninterior region may be affected by current or past diseases or injuries,previous exposure to ionizing radiation, pregnancy or lactation, geneticpredispositions, past or current exposure to various environmentalconditions, diet, past or current medications or treatments, level ofactivity, or other conditions. Sensitivity of an interior region of user11 may be determined by stem cell content or concentration, or by afraction of cells in that interior region that are dividing.

Radiation protection device 10 may be configured to enable user 11 tomove in a manner that is appropriate to planned activities of user 11.For example, radiation protection device 10 may be configured to enableat least limited (e.g., sufficient to enable a planned activity) bendingof a torso, one or more limbs, or another part of user 11. For example,rigid shield elements of a garment of radiation protection device 10 maybe embedded or otherwise incorporated into a flexible or elasticsubstrate. The sizes and shapes of rigid shield elements, as well as theseparation distance between adjacent rigid shield elements, may beconfigured to enable a predetermined degree of bending (e.g., maximumcurvature) of the garment. The flexible substrate may deform in variousways to allow compression or stretching to accommodate bending of theradiation protection device 10 and to ensure freedom of movement of user11. Layers of radiation protection device 10 may be configured to slidepast one another to facilitate bending of radiation protection device10. At least some of the shield elements may be pliable to at least alimited extent (e.g., liquid-filled sacs or bags).

In some cases, radiation protection device 10 may be configured to beintegrated into shielding of a spacecraft or cabin. For example, attimes when radiation protection device 10 need not be worn by user 11(e.g., when no solar particle event is occurring), radiation protectiondevice 10 may be removed and stowed. Walls of the cabin or spacecraftmay be configured such that radiation protection device 10 may beattached to the wall. For example, the wall may be provided with clipsor other structure that facilitate attachment of radiation protectiondevice 10 to the wall. When attached to the wall, radiation protectiondevice 10 may provide additional protection to the interior of thespacecraft or cabin, e.g., from galactic cosmic radiation or otherradiation.

In accordance with an embodiment of the present invention, radiationprotection device 10 may include several layers of protective garments.

FIG. 2 schematically illustrates garment layers of a section of theradiation protection device shown in FIG. 1.

Radiation protection device 10 includes three garment layers: innergarment layer 12 a, middle garment layer 12 b, and outer garment layer12 c. A radiation protection device 10 may include less than threelayers or more than three layers.

The thickness of each garment layer may not be constant. The thicknessof any particular layer may vary in order to provide selective shieldingto different surface regions of the body. Alternatively, selectivecoverage may be achieved by stacking additional layers over particularsurface regions.

In some cases, each pair of adjacent garment layers (e.g., inner garmentlayer 12 a and middle garment layer 12 b or middle garment layer 12 band outer garment layer 12 c) may be free to slide relative to oneanother. Such free sliding may facilitate bending or other movement ofuser 11. For example, the facing surfaces of the pairs of adjacentlayers may be free of any projections or indentations that could impedelateral movement of one layer relative to another. The facing surfacesmay be configured (e.g., with a nonstick coating) to facilitate relativesliding between the adjacent layers. For example, one or more of thefacing surfaces may be made of, or coated with, one or more frictionreducing materials. Such materials may include, for example,polytetrafluoroethylene, polyamide-imide, nylon 6-6, nylon 4-6,graphite, graphite powder, acetal homopolymer, carbon fiber, or anotherfriction-reducing material. In some cases, the innermost and outermostsurfaces (e.g., an inward-facing surface of inner garment layer 12 a oran outward-facing surface of outer garment layer 12 c) may be configuredso as to prevent snagging or friction between radiation protectiondevice 10 and any surface (e.g., skin or clothing) under inner garmentlayer 12 a or over (e.g., a protective suit for extravehicular activity)outer garment layer 12 c.

Each of the inner garment layer 12 a, middle garment layer 12 b, andouter garment layer 12 c includes a plurality of shield elements 14 thatare incorporated into a flexible substrate 16. For example, shieldelements 14 may be embedded in flexible substrate 16, as shown in FIG.2. Alternatively or in addition, shield elements 14 may be attached to asurface (e.g., an outer surface) of flexible substrate 16, inserted in apocket or sleeve of flexible substrate 16, or otherwise attached toflexible substrate 16.

Shield elements 14 may be configured to attenuate one or more types ofradiation. For example, in order to attenuate ionizing radiation in theform of energetic particles (e.g., solar wind particles, galactic cosmicray particles, or other ions, neutrons, or other particles), shieldelements may include materials that are composed of light nuclei (e.g.,hydrogen, carbon, oxygen, or other light nuclei). For example, shieldelements 14 may include polyethylene, polypropylene, or anotherhydrocarbon, water, or another material composed primarily of elementshaving a low atomic mass. In order to attenuate ionizing radiation inthe form of energetic photons (e.g., x-rays or gamma rays, e.g.,resulting from interaction of energetic charged particles with matter),shield elements 14 may include a material with a high atomic number. Forexample, shield elements 14 may include a metal (e.g., lead, gold,silver, tungsten, or another metal) or a metallic alloy in the form of apowder, pellets, coating, lining, layer, or another form. For example, apowder or pellet may have a particle diameter or other characteristicdimension in the range from less than a micrometer to about amillimeter.

In some cases, shield elements 14 may have a composition that is similarto that of flexible substrate 16. However, the density of the materialof shield elements 14 may be denser than that of flexible substrate 16.For example, shield elements 14 may include high density polyethylene,while flexible substrate 16 includes low density polyethylene (e.g.,polyethylene foam or fabric).

Each shield element 14 may be separated from an adjacent shield element14 by a section of flexible substrate 16 forming a gap. Shield elements14 in inner garment layer 12 a, middle garment layer 12 b, and outergarment layer 12 c may be configured such that a shield element 14 inone of the layers covers a gap in another of the layers. Thus, innergarment layer 12 a, middle garment layer 12 b, and outer garment layer12 c of radiation protection device 10 may be configured such that allsurface regions of a user 11 that are covered by radiation protectiondevice 10 are protected from incident radiation.

For example, shield elements 14 a in inner garment layer 12 a areseparated by a gap 18 a Similarly, shield elements 14 b in middlegarment layer 12 b are separated by a gap 18 b that is approximatelyaligned laterally to overlie gap 18 a. However, in outer garment layer12 c, shield element 14 c overlies approximately aligned gaps 18 a and18 b. Thus, a surface region of the body of a user 11 underlyingapproximately aligned gaps 18 a and 18 b may be protected by shieldelement 14 c Similarly, a surface region of the body of a user 11 thatunderlies gaps 18 c in outer garment layer 12 c may be protected byshield elements 14 b and 14 a that underlie gaps 18 c.

In some cases, user 11, or a cabin, spacecraft, space suit, or otherenclosure surrounding user 11, may be provided with one or moredosimeters or other radiation sensors. For example, the radiation sensormay measure a radiation level in an area where user 11 is found. Theradiation sensor may measure the level of radiation that is incident onone or more interior regions of the body of user 11. The result of theradiation measurement may be utilized in determining whether or notradiation protection device 10 need be worn, the recommended type ofgarment of radiation protection device 10 that is to be worn (e.g., whenmore than one type is available), and the number and selection ofgarment layers of radiation protection device 10 that are recommended tobe worn.

In accordance with an embodiment of the present invention, shieldelements 14 may be embedded or inlaid in flexible substrate 16, e.g., inthe form of a flexible matrix or foam.

FIG. 3A schematically illustrates a layer of a radiation protectiondevice with shield elements that are embedded in a flexible substrate,in accordance with an embodiment of the present invention.

In radiation protection garment 20, a section of which is shown in FIG.3A, embedded shield elements 22 are embedded in flexible substrate 16.For example, each embedded shield element 22 may be in the form ofsubstantially rigid plug. Each plug is at least partially surrounded bya flexible and elastic material forming flexible substrate 16.

Embedded shield elements 22 and flexible substrate 16 of radiationprotection garment 20 may be produced by application of one or moremolding, extrusion, injection, machining, or adhesion or otherproduction processes. For example, embedded shield elements 22 may bemolded or machined out of a substantially rigid material. Embeddedshield elements 22 may be positioned in a fixture into which materialfor forming flexible substrate 16 may be injected. As another example,openings or indentations for accommodating embedded shield elements 22may be punched or otherwise machined out of a layer of material formingflexible substrate 16. Plugs of substantially rigid material for formingembedded shield elements 22 may be inserted into the openings orindentations and caused to adhere to flexible substrate 16.

For example, embedded shield elements 22 may include high-densitypolyethylene. Flexible substrate 16 may include polyethylene foam.Alternatively or in addition, flexible substrate 16 may include anothertype of material that is sufficiently thick so as to incorporateembedded shield elements 22 but sufficiently flexible or elastic so asenable bending of radiation protection garment 20.

Alternatively or in addition, embedded shield elements 22 or flexiblesubstrate 16 may include a polymeric mixture that includes one or moreof polyurethane, polyamide, polyvinyl chloride, polyvinyl alcohol,natural latex, polypropylene, ethylene vinyl acetate, polyester, oranother polymer. One or more components may include an additive toimprove the flexibility, strength, durability, or another property ofthe polymeric mixture or to ensure that the polymeric mixture has anappropriate uniformity and consistency. For example, an additive mayinclude a plasticizer (e.g., epoxy soybean oil, ethylene glycol,propylene glycol, or another plasticizer), an emulsifier, a surfactant,a suspension agent, a leveling agent, a drying promoter, a flowenhancer, or other additive. A radiation attenuating material includedin embedded shield elements 22 may include one or more of carbonnano-materials with absorbed hydrogen, metal hydrides such as LiH, MgH₂,LiBH₄, NaBH₄, BeH₂, TiH₂ or ZrH₂, palladium (and alloys) with absorbedhydrogen, hydrocarbons (polyethylene or (CH₂)_(n)) with boron,quasi-crystals (e.g., TiZrNi), condensed hydrogen (solid and liquid),water (H₂O), drinking water, cooling liquid, and other hydrogen richmaterials or mixtures such as urine.

A particular isotope of an element may be selected for the shieldingmaterial in some cases. For example, a particular isotope may have arelatively (e.g., to other isotopes) large nuclear cross section for aparticular nuclear reaction. For example, boron-10 has a high crosssection for neutron capture.

Hydrogen is unique in its interaction with high-energy nuclei componentsof galactic cosmic rays which have an electric charge greater than +2because it cannot fragment into smaller nuclei. Polyethylene (C₂H₄)contains 14% hydrogen by mass fraction. Therefore, nano-materialcomposites using a polyethylene matrix are particularly attractive as aprimary component in a novel shielding material. A number ofnano-material additives are suitable for loading this and othermatrices. Such additives may include carbon nanostructures (fullerenes,nanotubes, graphene, nano-onions), metal hydride nanoparticles(including LiH, LiBH₄, BeH₂), boron nitride/boron carbide nanoparticles(offer both good strengthening characteristics as well as neutronabsorption), alkylated-fluorinated nanotubes (to promote dispersionwithin the matrix and increase mechanical properties), graphenenanoplatelets (carbon nanotube co-reinforced high-density polyethylenecomposites), and high-density polyethylene fibers woven with carbonnanotube yarn (to form flexible deployable radiation shieldingblankets).

For example, embedded shield elements 22 may be rigid and substantiallyincapable of being bent by forces that are typically exerted by a personwho is wearing radiation protection garment 20. Each embedded shieldelement 22 may have a tapered profile (e.g., a profile with anapproximately trapezoidal shape). Thus, a separating strip 24 offlexible substrate 16 that separates adjacent embedded shield elements22 may have a wedge-like profile.

For example, each embedded shield element 22 may have an inward-facingsurface with a surface area that is greater than the surface area of anopposite, outward-facing surface. Thus, a separating strip 24 offlexible substrate 16 that separates adjacent embedded shield elements22 may form a tapering gap (e.g., with an approximately triangular,wedge-like profile, or other tapering profile).

For example, radiation protection garment 20 may be formed by placementof shielding elements to form embedded shield elements 22 in anarrangement that corresponds to the positions of embedded shieldelements 22 in radiation protection garment 20. Spaces or gaps that areformed in between the shield elements may be fully or partially filledwith a flexible material (e.g., a polymer foam or other flexiblematerial) to form flexible substrate 16 in the form a matrix of theflexible material.

The flexibility and elasticity of flexible substrate 16 and ofseparating strips 24 may radiation protection garment 20 with sufficientflexibility to enable radiation protection garment 20 to bend togetherwith a person who is wearing radiation protection garment 20.

FIG. 3B schematically illustrates bending of the garment layer shown inFIG. 3A.

When a section of radiation protection garment 20 is bent, the openingangle of the wedge-like profile of separating strips 24 may increase ordecrease.

For example, when a section of radiation protection garment 20 is bentsuch that surface 21 a of radiation protection garment 20 is locallyconvex and surface 21 b is locally concave, separating strips 24 in thatsection may be stretched widthwise. When, stretched widthwise, theopening angle of the wedge-like profile may be increased, as shown forstretched separating strip 24 a Similarly, when a section of radiationprotection garment 20 is bent such that surface 21 a of radiationprotection garment 20 is locally concave and surface 21 b is locallyconvex, separating strips 24 in that section may be compressedwidthwise. When, compressed widthwise, the opening angle of thewedge-like profile may be decreased, as shown for compressed separatingstrip 24 b.

Two or more radiation protection garments 20 may be worn as layers overone another.

FIG. 4A schematically illustrates an inner garment layer with embeddedshield elements of a radiation protection device, in accordance with anembodiment of the present invention. FIG. 4B schematically illustrates amiddle garment layer with embedded shield elements worn over the innergarment layer shown in FIG. 4A. FIG. 4C schematically illustrates anouter garment layer with embedded shield elements worn over the garmentlayers shown in FIG. 4B.

For example, inner radiation protection garment 20 a may be worndirectly over personal clothing (e.g., the clothing worn when noradiation protection is required) or skin of user 11. Middle radiationprotection garment 20 b may be worn over inner radiation protectiongarment 20 a. Outer radiation protection garment 20 c may be worn overmiddle radiation protection garment 20 b. When all of the garment layersare worn, embedded shield elements 22 on the different garment layersmay be so aligned with one another as to provide a predetermined degreeof protection (e.g., attenuation) to all covered parts of user 11.

In accordance with an embodiment of the present invention, a garment ofa radiation protection device may include one or more sheets of shieldelements in the form of sequins. The flexible substrate to which theshield elements are attached may include a sheet of flexible material towhich the shield elements are attached, or flexible webbing thatconnects the shield elements to one another.

In accordance with an embodiment of the present invention, a garment ofa radiation protection device may include shield elements in the form ofpackets of a liquid. The packets may be inserted into pockets or sleevesin a flexible substrate.

FIG. 5A schematically illustrates an inner garment layer of a radiationprotection device, the layer having shield elements in the form ofsequins, in accordance with an embodiment of the present invention. FIG.5A schematically illustrates an inner garment layer of a radiationprotection device, the garment layer having shield elements in the formof sequins, in accordance with an embodiment of the present invention.FIG. 5B schematically illustrates a middle garment layer with shieldelements in the form of sequins and worn over the inner garment layershown in FIG. 5A.

For example, inner sequined radiation protection garment 30 a may beworn directly over personal clothing or skin of user 11. Middle sequinedradiation protection garment 30 b may be worn over inner sequinedradiation protection garment 30 a.

FIG. 5C schematically illustrates an outer garment layer with liquidshield elements worn over the garment layers shown in FIG. 5B.

Liquid-fillable radiation protection garment 32 may be worn over middlesequined radiation protection garment 30 b. Liquid-fillable radiationprotection garment 32 includes a plurality of bag holders 34. Forexample, each bag holder 34 may be in the form of a sleeve or pocketinto which a liquid bag 38 may be inserted. Each bag holder 34 may beprovided with bag retaining structure 36 that is configured to preventaccidental or unintentional removal of a liquid bag 38 from bag holder34. For example, bag retaining structure 36 may include a sealable flap,strap, or lip. Bag retaining structure 36 may be provided with a button,zipper, snap, hook-and-loop fastener, magnet, adhesive or tacky surface,or other structure to hold closed bag retaining structure 36.

Bag holders 34 may be made of a flexible material to form a flexiblesubstrate of liquid-fillable radiation protection garment 32. Similarly,liquid bags 38 may be made of a flexible material. In some cases, thematerial of bag holders 34, of liquid bag 38, or of both may be elastic.

Liquid bag 38 may be filled with water or another liquid. For example,liquid-fillable radiation protection garment 32 may be utilized forstorage of potable water for drinking, e.g., during extravehicularactivity or as an emergency supply when other sources of drinking waterare unavailable. Liquid bag 38 may be filled with urine or otherwastewater. For example, liquid-fillable radiation protection garment 32may be used to temporarily store wastewater for later purification by apurification device. Liquid bag 38 may be filled with another liquid.

Liquid layer sections 50 of liquid-fillable radiation protection garment32 may be configured as a plurality of stacked liquid-fillable layers.For example, liquid layer sections 50 may be configured such thatradiation traverses a greater distance through (or, equivalently, agreater areal density of) a liquid filling liquid-fillable radiationprotection garment 32 than another section of liquid-Tillable radiationprotection garment 32. For example, a liquid layer section 50 may bedesigned to be worn over an interior region of elevated sensitivity toradiation (e.g., more sensitive than other interior regions of user 11,such as a stem cell niche or other interior region of highersensitivity) of user 11.

FIG. 5D schematically illustrates a cross of a liquid layer section ofthe outer garment layer with liquid shield elements shown in FIG. 5C.

Liquid layer section 50 includes a plurality of liquid-fillablecompartments 52 that are stacked atop one another.

Each liquid-fillable compartment 52 of liquid layer section 50 may be inthe form of a bag or pouch of a flexible or elastic material. Tube 54may provide support for maintaining a shape of liquid layer section 50.In addition, tube 54 may be used to fill one or more liquid-Tillablecompartments 52, or to remove liquid from one or more liquid-fillablecompartments 52. For example, tube 54 may be made of a durable materialwith limited flexibility, such as polyethylene, polypropylene, anotherthermoplastic, another polymer, carbon fiber, a metal, or anothermaterial that is suitable for forming a tube that provides support orliquid access.

Tube 54 may be used to conduct liquid from tube opening 56 to one ormore liquid-fillable compartments 52. Tube opening 56 may be accessiblefrom outside of liquid-Tillable radiation protection garment 32. In somecases, tube opening 56 may be provided with a cap or other closure thatmay be opened in order to access tube opening 56. For example, the capor closure may be configured to pad or cover tube opening 56 in order toprevent any damage or injury that could occur by a collision with tubeopening 56.

For example, tube 54 may be provided with one or a plurality ofliquid-permeable segments 58 that are configured to enable flow ofliquid between tube 54 and a corresponding one or a plurality ofliquid-Tillable compartments 52. For example, a liquid-permeable segment58 may include perforations or openings to enable liquid to flow betweentube 54 and a liquid-fillable compartment 52. Alternatively or inaddition, a liquid-permeable segment 58 may include a porous material toenable flow of liquid between tube 54 and a liquid-fillable compartment52.

For example, prior to use of liquid-Tillable radiation protectiongarment 32, a liquid may be introduced into one or more liquid-fillablecompartments 52 via tube opening 56 and tube 54. When liquid layersection 50 is to be emptied, or when liquid in a liquid-Tillablecompartment 52 is withdrawn for drinking or for another purpose, theliquid may be removed from liquid-fillable compartments 52 via tube 54and tube opening 56.

Tube 54 may be provided with one or more valves 60. Each valve 60 may benormally shut (e.g., preventing flow of liquid in either direction). Inthis case, a valve 60 may be opened by application of inward pressure totube opening 56 (e.g., to introduce a liquid into liquid-fillablecompartments 52 via valves 60), or by application of suction to tubeopening 56 (e.g., to suck liquid out of liquid-fillable compartments 52via valves 60) or pressure to one or more liquid-Tillable compartments52 (e.g., to squeeze liquid out of liquid-Tillable compartments 52). Insome cases, a valve 60 may be directional valve that enablessubstantially unimpeded flow in one direction while preventing orimpeding flow in the opposite direction. In some cases, a valve 60 maybe opened by insertion of a rod or tube (e.g., straw) into valve 60 viatube opening 56, by application of a lateral (e.g., lateral squeezingforce) to valve 60, or by other structure that is configured to enablecontrol over opening or closing of a valve 60.

For example, in some cases, a valve 60 (such as valve 60 a) may beprovided to control flow of liquid into or out of tube 54 via tubeopening 56. In some cases, a valve 60 may be located betweenliquid-permeable segments 58 that connect to different liquid-fillablecompartments 52. For example, such valves 60 may be utilized toselectively fill or withdraw liquid from one or more selectedliquid-fillable compartments 52.

Use of water to fill liquid bag 38 may be advantageous. Water may beeffective at attenuating radiation in the space environment. Water alsoserves multiple purposes and is necessary for manned space missions. Itsdual usage as a radiation attenuating material is favorable from apayload perspective. Water is always included in crew modules of spacevehicles and in space suits.

A sequined radiation protection garment, such as inner sequinedradiation protection garment 30 a, middle sequined radiation protectiongarment 30 b, or another sequined radiation protection garment, may beconfigured to attenuate radiation while enabling flexibility. Theflexibility may be sufficient to enable user 11 to bend so as not impedeuser 11 in the performance of a one or more anticipated tasks. Thesequined radiation protection garment may include one or more flexiblesheets of sequins. As used herein, a sequin refers to any solid objectthat may be incorporated with a plurality of similar objects into agarment. For example, the sequins may include objects that are similarto buttons, medallions, beads, studs, naps, or similar objects.

FIG. 6A schematically illustrates a sheet of the sequin shield elementgarment layer shown in FIG. 5A.

Sequin sheet 40 includes a flexible sequin substrate 42 to which aplurality of shield sequins 44 are attached.

For example, flexible sequin substrate 42 may consist of a natural orsynthetic fabric. For example, flexible sequin substrate 42 may includea woven or otherwise produced fabric that enables at least limitedpassage of air or gasses. Alternatively or in addition, flexible sequinsubstrate 42 may include a film, foam, or other flexible material.Flexible sequin substrate 42 may include a polyethylene fabric.Alternatively or in addition, flexible sequin substrate 42 may include apolymeric fabric, such as polychloroprene (e.g. neoprene),polypropylene, aramid fiber, rayon, nylon, or another polymeric fabric.

Flexible sequin substrate 42 may be in the form of a continuous sheet towhich shield sequins 44 are attached. For example, shield sequins 44 maybe attached to flexible sequin substrate 42 by tying on, sewing orweaving, glue or other adhesive, welding, magnets, staples, screws,rivets, clips, or otherwise. Alternatively or in addition, flexiblesequin substrate 42 may be in the form of webbing that connects edges ofshield sequins 44 to one another. For example, flexible sequin substrate42 may be attached to edges of shield sequins 44 by sewing, adhesive,welding, or otherwise.

Shield sequins 44 may be sufficiently rigid so as not to bend duringtypical activity of a person wearing a garment that includes sequinsheet 40. Substantially all flexibility of sequin sheet 40 may beprovided by flexible sequin substrate 42.

Shield sequins 44 may be hexagonally shaped as shown. Alternatively orin addition, some or all shield sequins 44 may be otherwise shaped(e.g., square, rectangular, triangular, polygonal, circular, oval, oranother shape). In some cases, hexagonally shaped shield sequins 44 mayenable an optimum balance between coverage of sequin sheet 40 by shieldsequins 44 and flexibility of sequin sheet 40.

Each shield sequin 44 is configured to attenuate one or more types ofionizing radiation. For example, shield sequins 44 may be configured toattenuate radiation in the form of energetic particles. Thus, shieldsequins 44 may include a solid material with a high density of lightnuclei, such as high-density polyethylene. Alternatively or in addition,may include another solid polymer, hydrocarbon, or other material with ahigh density of light. In some cases, shield sequins 44 may beconfigured to attenuate radiation in the form of high energy photons. Inthis case, shield sequins 44 may include a heavy metal or other materialwith a high atomic number. In some cases, shield sequins 44 may beconfigured to attenuate both particulate and photonic radiation. Forexample, shield sequins 44 may include metallic powder or particles thatare embedded in a solid polymer.

A sequined radiation protection garment, such as inner sequinedradiation protection garment 30 a or middle sequined radiationprotection garment 30 b, may include two or more layered sequin sheets40.

FIG. 6B schematically illustrates multiply layered sheets of the sequinshield element garment layer shown in FIG. 5A.

A section of sequined radiation protection garment 30 includes aplurality of layered sequin sheets 40. Each sequin sheet 40 thatoverlies another sequin sheet 40 may be connected to that underlyingsequin sheet 40 at one or more edges of the overlying sequin sheet 40.The connection of an overlying sequin sheet 40 to an underlying sequinsheet 40 may enable the overlying sequin sheet 40 to slide over theunderlying sequin sheet 40.

For example, faces of shield sequins 44 may be smooth or coated with anonstick or low-friction material to facilitate to movement betweenadjacent layered sequin sheets 40. Such materials may include, forexample, polytetrafluoroethylene, polyamide-imide, nylon 6-6, nylon 4-6,graphite, graphite powder, acetal homopolymer, carbon fiber, or anotherfriction-reducing material. Alternatively or in addition, edges ofshield sequins 44 may be rounded to prevent the shield sequins 44 ofadjacent layered sequin sheets 40 from catching on one another.

For example, when intended for use on a planet surface or otherenvironment with natural or artificial gravity, a top edge of theoverlying sequin sheet 40 may be sewn or otherwise attached (e.g.,stapled, glued, zipped, snapped, buttoned, clipped, or otherwiseattached) to the underlying sequin sheet 40. Thus, the overlying sequinsheet 40 may be draped over the underlying sequin sheet 40. Thus, afree, unattached end of the overlying sequin sheet 40 may be free toslide over the underlying sequin sheet 40, e.g., when sequined radiationprotection garment 30 is arched, folded, or otherwise flexed or bent.

When intended for use under weightless conditions, more than one edge ofthe overlying sequined radiation protection garment 30 may be sewn orotherwise attached to the underlying sequin sheet 40. For example, inorder to enable relative movement between adjacent layered sequin sheets40, one or more edges of the overlying sequin sheet 40 may beelastically attached to the underlying sequin sheet 40. For example, anedge of the overlying sequin sheet 40 may be sewn, tethered, tied orotherwise attached to the underlying sequin sheet 40 via one or moreelastic threads, bands, or other elastic connection.

Sequin sheets 40 may be layered in order to ensure that radiationprotection is provided to all surface regions of a person that arecovered by sequined radiation protection garment 30. For example, ashield sequin 44 of an overlying sequin sheet 40 may overlie gap 46between adjacent shield sequins 44 of an underlying sequin sheet 40. Inthis manner, all gaps 46 in underlying layered sequin sheets 40 may becovered by one or more shield sequins 44 of one or more overlying sequinsheets 40.

In some cases, the number of layered sequin sheets 40 in a section ofsequined radiation protection garment 30 may be determined by a degreeof protection (quantified by an amount of attenuation) that is to beprovided for a surface region of a person's body that the section isconfigured to cover. For example, a section of sequined radiationprotection garment 30 that is configured to cover a body region that ismore sensitive to ionizing radiation may include more layered sequinsheets 40 than a section that is configured to cover a body region thatis less sensitive to the radiation.

Layered sequin sheets 40 of sequined radiation protection garment 30 maybe configured to slide over one another when sequined radiationprotection garment 30 is bent.

FIG. 6C schematically illustrates bending of the sequin shield elementgarment layer shown in FIG. 6B.

In the example shown, overlying sequin sheet 40 b overlies underlyingsequin sheet 40 a (plus additional intervening sequin sheets 40).Sequined radiation protection garment 30 is bent such that a surface ofsequined radiation protection garment 30 that is closest to overlyingsequin sheet 40 b is bent convexly. During the bending, overlying sequinsheet 40 b may slide relative to underlying sequin sheet 40 a in thedirection indicated by arrow 48 (e.g., toward an edge of overlyingsequin sheet 40 b that is attached to underlying sequin sheet 40 a).When bending in the opposite direction, the surface of sequinedradiation protection garment 30 that is closest to overlying sequinsheet 40 b is bent concavely. During this opposite bending, overlyingsequin sheet 40 b may slide relative to underlying sequin sheet 40 aopposite the direction indicated by arrow 48 (e.g., in a direction awayfrom an edge of overlying sequin sheet 40 b that is attached tounderlying sequin sheet 40 a).

A liquid-fillable radiation protection garment 32, e.g., that isconfigured to be worn over sequined radiation protection garment 30 orotherwise, may be configured to enable bending of a person wearingliquid-fillable radiation protection garment 32.

FIG. 7 schematically illustrates bending of the garment layer withliquid shield elements of the radiation protection device shown in FIG.5C.

When liquid-Tillable radiation protection garment 32 is bent as shown,concave liquid-Tillable garment section 32 a is compressed in thedirection indicated by compression arrows 50 a while convexliquid-Tillable garment section 32 b is stretched in the directionindicated by stretching arrows 50 a. When concave liquid-Tillablegarment section 32 a is compressed, bag holders 34 a (each filled with aliquid bag 38) in concave liquid-fillable garment section 32 a arepressed together in the direction indicated by compression arrows 50 aso as to bulge outward. Similarly, when convex liquid-fillable garmentsection 32 b is stretched, bag holders 34 b in convex liquid-fillablegarment section 32 b are pulled away from one another in the directionindicated by stretching arrows 50 b. When so pulled apart, the outersides of bag holders 34 b may be sucked inward (reducing theircurvature).

A radiation protection device in accordance with an embodiment of thepresent invention may be provided as part of applying a method forpreventing diseases that may be induced by exposure to radiation, or towhich a person may be predisposed due to exposure to radiation. Forexample, the method may be applied to reduce the likelihood ofmalignancies. In particular, the method may be applied to reduce thelikelihood a condition such as a cancer of the hematologic progenitorcells, leukemia, depressed immune system, or radiation sickness.

FIG. 8 is a flowchart depicting a method for preventing aradiation-related condition in a living body, in accordance with anembodiment of the present invention.

It should be understood with respect to any flowchart referenced hereinthat the division of the illustrated method into discrete operationsrepresented by blocks of the flowchart has been selected for convenienceand clarity only. Alternative division of the illustrated method intodiscrete operations is possible with equivalent results. Suchalternative division of the illustrated method into discrete operationsshould be understood as representing other embodiments of theillustrated method.

Similarly, it should be understood that, unless indicated otherwise, theillustrated order of execution of the operations represented by blocksof any flowchart referenced herein has been selected for convenience andclarity only. Operations of the illustrated method may be executed in analternative order, or concurrently, with equivalent results. Suchreordering of operations of the illustrated method should be understoodas representing other embodiments of the illustrated method.

Operations of radiation protection method 100 may be executed by aperson who is designing or assembling a radiation protection device, inaccordance with an embodiment of the present invention. For example, theradiation protection device may be designed for a particular person foruse under one or more predetermined conditions. Radiation protectionrequirements for a person (e.g., a maximum allowable radiation dose orexposure) may be determined by one or more characteristics of the personto be protected. The predetermined conditions may be related toanticipated locations of the person and anticipated activities of theperson at the anticipated locations.

A required total attenuation (A_(R)) may be determined (block 110).

The required total attenuation may vary according to the use for whichthe radiation protection device is intended. For example, when intendedfor continued use involving lengthy exposure to radiation, A_(R) may berelatively high. Such a configuration may be applicable to firstresponders who remain in disaster zones and to interplanetary spacetravel. When intended for short term use, A_(R) may be relatively low.Such a configuration may be applicable to individuals being evacuatedfrom disaster zones.

The determination of A_(R) may be such that a radiation-inducedcondition is prevented under an anticipated exposure of the person toradiation.

For example, the determination of A_(R) may be such that the survivingvolume of active bone marrow is sufficient to allow for hematopoieticreconstitution after exposure. For example, this volume may rangebetween 23 cm³ and 58 cm³ of active marrow, depending on the size of theindividual. In some cases, A_(R) may be calculated by

${A_{R} \geq \frac{D_{U}}{D_{V}}},$where D_(U) is the unprotected radiation dose and D_(V) is the dose atwhich the required percent viability of bone marrow is the requiredvolume for hematopoietic reconstitution.

For example, if the intended use requires exposure to 1000 rad/hour forone hour (D_(U)=1000 rad), and the radiation protection device protectsin a substantially uniform manner 150 cm³ of active bone marrow, and 41cm³ of bone marrow is required to survive, then the level of protectionis required to be 27%. A maximum allowable dose for 27% survival of bonemarrow cells may be 200 rad (D_(V)). Thus, A_(R) for this case is 5.

A required attenuation by the radiation protection device (A_(D)) may becalculated (block 120).

For example, various imaging technologies (e.g., computed tomography,magnetic resonance imaging, or other imaging) may be used to determinethe nature of tissue that surrounds an interior region of the body thatis to be protected. For example, the analysis may be particular to aparticular person, or may be based on a population of similar people.Based on the characteristics (e.g., composition and dimensions) ofsurrounding tissue, tissue attenuation A_(T) may be determined. Theattenuation A_(D) may then be determined from A_(R) and A_(T) (for apoint at coordinates x, y, z) by

${A_{D}\left( {x,y,z} \right)} = {\frac{A_{R}}{A_{T}}.}$

In the above example, where A_(R) is calculated to be 5 and if A_(T) isdetermined to be 2, A_(D) may be required to be 2.5.

FIG. 9A schematically illustrates a front part of a map of selfshielding by body tissue of radiation sensitive interior regions in aperson, for use in design of a radiation protection device in accordancewith an embodiment of the present invention. FIG. 9B schematicallyillustrates a rear part of the self-shielding map shown in FIG. 9A.

Self-shielding map 70 indicates the areal density of shielding (e.g., inunits of g/cm2 as indicated by legend 72) that is provided by bodytissue of a person to one or more radiation sensitive interior regionswithin the person's body. In the example, shown, the radiation sensitiveinterior regions include the ovaries, stomach, colon, glandular breasttissue, hematopoietic stem cells of the iliac crest, and tissue residentstem cells in the distal airways of the lungs.

For example, self-shielding densities of self-shielding map 70 may becalculated on the basis of one or more of measurements on human bodies,measurements on phantoms, measurements on animals, simulations,calculations based on a model, or another technique for determiningself-shielding by human tissue. Other quantities may be used to indicateself-shielding by human tissue (e.g., transmission, attenuation, oranother quantity indicative of self-shielding by tissue).

For example, self-shielding to the radiation-sensitive interior regionsmay be determined by tracing rays that originate from theradiation-sensitive interior regions to the surface of the body. Thelocal distance and density of the tissue (e.g., bone, muscle, adipose,or other tissue) that is traversed by each ray may be multiplied andintegrated along the path of the ray.

A radiation protection device is provided that provides the calculateddevice attenuation (block 130).

In some cases the required thickness of shielding (e.g., number or sizeof shield elements) that cover that interior region may be calculated asln(A_(D))/μ, where μ is the linear attenuation coefficient (e.g., inunits of cm⁻¹). In some cases, e.g., where radiation scatteringsignificantly contributes to the attenuated radiation, other factors(e.g., a buildup factor or other factor) may be taken into account whencalculating the required thickness.

FIG. 10A schematically illustrates a map of a distribution of radiationshielding on a front of a radiation protection device that is designedin consideration of the self-shielding map shown in FIG. 9A. FIG. 10Bschematically illustrates a map of a distribution of radiation shieldingon a rear of a radiation protection device that is designed inconsideration of the self-shielding map shown in FIG. 9B.

Device shielding map 74 indicates the areal density of shielding (e.g.,in units of g/cm2 as indicated by legend 72) that is provided by aradiation protection device when worn by a person. For example,shielding densities of device shielding map 74 may be calculated on thebasis of one or more of a design of the radiation protection device,measurements (e.g., of radiation transmission) of a radiation protectiondevice, or another technique for determining shielding by a radiationprotection device. Other quantities may be used to indicate shielding bya radiation protection device (e.g., transmission, attenuation, oranother quantity indicative of shielding by the radiation protectiondevice).

A radiation protection device whose shielding is as indicated by deviceshielding map 74 may be worn on by a person whose self-shielding is asindicated by self-shielding map 70. In this case, the total shielding ofsensitive interior region of the person may be found by combining theshielding that is indicated by the combination of device shielding map74 and self-shielding map 70 (e.g., additively combining when arealdensity is mapped, multiplicatively when attenuation is mapped, or usinganother appropriate the combination technique).

The total required radiation attenuation in areal density in order toachieve a desired absorbed dose reduction for a given material may bedetermined based on theoretical or experimentally determined values fora given spectrum of a mixed field of radiation. In order to provide agiven amount of desired attenuation (e.g., equivalent to 26 g/cm² arealdensity) to each radiation-sensitive interior region of the body, thethickness (e.g., areal density) of each shielding element may beselected to augment self-shielding of the radiation-sensitive interiorregion by the body such that for each point on the surface the arealdensity provided to each protected tissue/organ is at least 26 g/cm^2 byadding the areal density of self shielding plus the areal density of theshielding elements at each point. For example, if at a particular pointon the surface of the body there is 20 g/cm² of self-shielding by tissuebetween that point and the radiation-sensitive interior region, and ifthe density of the shielding elements that cover that point is 1 g/cm³,then the shielding elements at this point may be 6 cm thick with anareal density of 6 g/cm². Therefore, the thickness of the shielding overthe surface may vary widely based on the self-shielding at variouspoints and depending on the density of the shielding elements that covereach point.

A material may be selected in accordance with a type of radiation towhich a person is expected to be exposed. For example, the mosteffective material per unit mass of shield for radiation in space (e.g.,primarily energetic protons and other small nuclei from solar particleevents and galactic cosmic radiation) may be provided by hydrogen.Shields of heavier elements, lead for example, while commonly used forx- or γ-ray absorption, may be less efficient per unit mass than lighterelements for absorbing energetic nuclear particles (and may contributeto the radiation by producing short-range heavy nuclear fragments andpenetrating neutrons).

The radiation protection device may be worn by an astronaut or anotheruser in order to maximize the shielding thickness across the solid anglecovered. A radiation protection device may be designed so as to enablemovement by a person wearing the device. For example, under weightlessconditions, a physical thickness of the radiation protection device,rather than the total mass may be made sufficiently small so as not tolimit mobility. For example, use of graded shield elements consisting ofsuccessive layers of high density, high atomic number materials, and lowdensity, hydrogen-rich compounds may be utilized to reduce thickness (asis sometimes used for radiation hardening of active electroniccomponents).

Radiation shielding elements of the radiation protection device may bearranged in layers, or as separate layered garments. Such layering mayenable mobility of a user of the device. Furthermore, when worn asseparate layered garments, different combinations of garments may beutilized under different circumstances. For example, garments to be wornmay be selected in accordance with a planned activity and an anticipatedexposure to radiation during that activity.

Protection of various interior regions of a body of a person may bedesigned, or a design evaluated, using ray-tracing techniques or othertechniques for calculating exposure to radiation.

For example, in order to determine the ability of the radiationprotection device to protect a user wearing the device, radioisotopesources, particle (e.g., proton) accelerators (e.g., designed to mimicspace radiation), or other sources may be placed in a uniform patternaround an anatomically accurate human phantom. Radiation doses receivedat these concentrations in the presence and absence of the radiationprotection device may be measured. For example, an accurate phantom mayinclude a human skeleton with thermoluminescent dosimeters embedded inbone marrow centers and surrounded by water to simulate human tissue.The dose with and without the radiation protection device may becompared.

For example, foci of protection may be designated within the body. Thebody may be a standard body (e.g., based on a collection of internalmeasurements or images, such as is available via the Visible HumanProject), or may be based on interior imaging (e.g., computed tomographyor magnetic resonance imaging scans) of a particular body. The foci ofprotection may be defined as three-dimensional coordinates of the centerof masses of stem cell niches that are to be protected by the radiationprotection device. Such niches may include, for example, areas withinthe lungs, iliac red bone marrow, and ovaries which had the highestconcentrations of stem cells. For organs with bilateral stem cell niches(e.g., lungs, iliac red bone marrow, and ovaries), two foci ofprotection may be designated; one for each side.

For some radiation types, such as those encountered in space where theenergy spectrum is highly variable and the radiation field is mixed(different types of radiation may be incident simultaneously), radiationprotection method 100 may be modified.

The propagation of some radiation types, such as protons and alpharadiation, is characterized by a Bragg peak. The Bragg peak correspondsto path length at which there is a sharp increase in energy depositionbefore the end of its track length. In this case, the required totalattenuation may be selected to ensure that the Bragg peak does not occurwithin a radiation-sensitive interior region. For example, if a spectrumof protons has a maximum energy of 100 MeV with a Bragg peak ending at77 g/cm² in liquid water (which has comparable stopping power to humanbody tissue), then the required total attenuation may be determined tobe at least 77 g/cm². If, at a particular point on the surface of thebody, the self-shielding of tissue that lies between the skin surfaceand a radiation-sensitive interior region is 55 g/cm², then theradiation protection device should provide 22 g/cm² of shielding at thatpoint. If the shielding elements are composed of liquid water with adensity of 1 g/cm³, then the shielding thickness at that point would be22 cm.

The areal density values for required total attenuation, self-shieldingattenuation, and shielding element attenuation may be adjusted based onthe total stopping power for a specific composition of a shieldingmaterial and a type of incident radiation.

The shielding elements used to shield one interior region of the bodymay be different from those used to shield another interior region. Forexample, ergonomic constraints (allowing range of motion andflexibility) may determine that denser (e.g., than water) materialsshould be used to shield some areas of the body in order to reduce therequired thickness. Similarly, ergonomic constraints may determine theflexibility of different sections of the radiation protection devicethat are configured to shield different interior regions of the body.

Different embodiments are disclosed herein. Features of certainembodiments may be combined with features of other embodiments; thuscertain embodiments may be combinations of features of multipleembodiments. The foregoing description of the embodiments of theinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. It should be appreciated bypersons skilled in the art that many modifications, variations,substitutions, changes, and equivalents are possible in light of theabove teaching. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

The invention claimed is:
 1. A device for protection of a body fromspace radiation, the device comprising: at least one flexible garment,each section of said at least one flexible garment being configured toshield a region of a surface of the body such that said each sectioncomplementarily attenuates self-shielding by internal structure betweensaid region and an interior region of the body such that space radiationat the interior region is attenuated to a predefined attenuation level,and a plurality of shield elements incorporated into a flexiblesubstrate of the at least one flexible garment, comprising a pluralityof bags, each of the bags being configured to be filled with a liquid.2. The device of claim 1, wherein the flexible substrate or saidplurality of shield elements comprises a polymer.
 3. The device of claim1, wherein said plurality of shield elements is embedded within theflexible substrate.
 4. The device of claim 1, wherein each of saidplurality of shield elements has an inward facing surface that isgreater than an opposite outward facing surface, such that tapering gapsare formed in between adjacent shield elements of said plurality ofshield elements.
 5. The device of claim 4, wherein the substrate fullyor partially fills the gaps.
 6. The device of claim 1 wherein theflexible substrate comprises a foam.
 7. The device of claim 1, whereinsaid plurality of shield elements comprises a plurality of sequins thatare attached to the flexible substrate and wherein the flexible surfacecomprises a fabric sheet.
 8. The device of claim 7, wherein the fabricsheet forms a webbing between said plurality of sequins.
 9. The deviceof claim 7, wherein a garment of said at least one garment comprises aplurality of the fabric sheets formed into layers.
 10. The device ofclaim 9, wherein a sequin of said plurality of sequins on one fabricsheet of said plurality of the fabric sheets is positioned to overlie agap between adjacent sequins of said plurality of sequins on anotherfabric sheet of said plurality of fabric sheets.
 11. The device of claim1, wherein the flexible substrate comprises a plurality of flexible bagholders, each of said plurality of bags being configured to be insertedinto a bag holder of said plurality of flexible bag holders.
 12. Thedevice of claim 1, wherein said at least one garment comprises aplurality of garments that are configured to be worn in layers, whereinone garment of said plurality of garments is configured such that ashield element of said plurality of shield elements on said one garmentis configured to overlie a gap between two adjacent shield elements onanother garment of said plurality of garments.
 13. The device of claim1, wherein the interior region includes tissue-resident stem cells. 14.The device of claim 13, wherein the tissue-resident stem cells areselected from a group of tissue-resident stein cells consisting ofdistal airway stem cells of the lung, CD34+ hematopoietic stem cells,and intestinal LGR5+ stem cells.
 15. A device for protection of a bodyfrom space radiation, the device comprising: at least one flexiblegarment, each section of said at least one flexible garment beingconfigured to shield a region of a surface of the body such that saideach section complementarily attenuates self-shielding by internalstructure between said region and an interior region of the body suchthat space radiation at the interior region is attenuated to apredefined attenuation level, and a plurality of shield elementsincorporated into a flexible substrate of the at least one flexiblegarment, wherein a shield element of said plurality of shield elementscomprises a plurality of stacked liquid-fillable compartments.
 16. Thedevice of claim 15, further comprising a tube to enable introduction ofa liquid into a liquid-fillable compartment of said plurality of stackedliquid fillable compartments or removal of the liquid frog aliquid-fillable compartment of said plurality of stacked liquid-fillablecompartments.
 17. A method for preventing a space radiation-inducedcondition in a body in space, the method comprising: determining arequired attenuation of space radiation at an interior region of thebody so as to prevent the space radiation-induced condition under ananticipated exposure of the body to space radiation; determiningself-shielding from the space radiation corresponding to each surfaceregion of a plurality of regions of a surface of the body by determiningattenuation of the radiation by internal structure of the body that liesbetween the interior region and said each surface region; providing aspace radiation protection device comprising at least one flexiblegarment, each section of said at least one flexible garment beingconfigured to attenuate space radiation to a shielded surface region ofplurality of regions of a surface of the body to complementarilyattenuate the self-shielding by the shielded surface region; andproviding a plurality of shield elements incorporated into a flexiblesubstrate of the at least one flexible garment and having a plurality ofbags, each of the bags being configured to be filled with a liquid. 18.The method of claim 17, wherein the space radiation-induced conditioncomprises mutagenesis or destruction of stem cells and the interiorregion comprises a stem cell niche.
 19. The method of claim 17, whereindetermining the required space radiation attenuation comprisesdetermining an attenuation required to prevent a Bragg peak of the spaceradiation from occurring within the interior region.
 20. The method ofclaim 17, wherein determining the required attenuation of spaceradiation comprises determining total areal density of shielding to theinterior region to prevent the space radiation-induced condition, thedetermined self-shielding comprises an areal density of the internalstructure that lies between the interior region and said each surfaceregion, and wherein an areal density of said each section is at least adifference between said total areal density and said areal density ofthe internal structure.
 21. The method of claim 17, wherein theplurality of bags comprise a plurality of stacked liquid-fillablecompartments.